1. Technical Field
The present invention relates generally to data integration technologies and, in particular, to techniques for authoring stylesheets in an XML application development environment.
2. Description of the Related Art
Organizations today are realizing substantial business efficiencies in the development of data intense, connected, software applications that provide seamless access to database systems within large corporations, as well as externally linking business partners and customers alike. Such distributed and integrated data systems are a necessary requirement for realizing and benefiting from automated business processes, yet this goal has proven to be elusive in real world deployments for a number of reasons including the myriad of different database systems and programming languages involved in integrating today's enterprise back-end systems.
Extensible Markup Language (XML) technologies are ideally suited to solve advanced data integration challenges, because they are both platform and programming language neutral, inherently transformable, easily stored and searched, and already in a format that is easily transmittable to remote processes via XML-based Web services technologies. XML is a subset of SGML (the Structured Generalized Markup Language) that has been defined by the World Wide Web Consortium (W3C) and has a goal to enable generic SGML to be served, received and processed on the Web. XML is a clearly defined way to structure, describe, and interchange data. XML technologies offer the most flexible framework for solving advanced data integration applications. They do not, however, encompass the entire solution, in that a particular solution must still be implemented. Thus, XML technologies are not a standalone replacement technology, but rather a complementary enabling technology, which when bound to a particular programming language and database provide an elegant solution to a different problem.
There are a number of ancillary technologies associated with XML. The extensible Stylesheet Language (XSL) consists of, among other things, the extensible Stylesheet Language Transformation (XSLT), a standardized language for transforming XML documents to simple output forms such as HTML or WML, and the extensible Stylesheet Language Formatting Objects (XSL:FO), an XML-based language for expressing advanced document layouts, employed by many popular formats including PDF and PostScript files. XSL decouples the contents of a document from its style (i.e., the document's layout and formatting). This allows a designer to either change the document's style without affecting the content, or to change the content while preserving the style. The transformation process from one data format to another involves processing an XML document and an XSL stylesheet in an XSL processor, which results in the generation of a new output document. An example of altering a document's style while preserving the content is multi-channel publishing. Using XSL, a single source of XML content can be published into a wide variety of customized output media, such as HTML, WML, PostScript, PDF, or any other information format, through the application of a stylesheet. An example of changing a document's content while preserving the style is internationalization and localization of resource files. A corporate website could internationalize its content in different languages such as German and Japanese, simply by translating the XML content and leaving the stylesheets unchanged.
A given output format, such as HTML, PDF, PostScript, or the like, has its own associated XSLT stylesheet. Thus, for a given XML document, a first XSLT stylesheet must be created to generate HTML, a second XSLT stylesheet must be created to generate PDF, a third XSLT stylesheet must be created to generate WML, and so forth. Because of the need to have a unique stylesheet for every output format, authoring XSLT stylesheets is an extremely complex and time-consuming task. Many designers have little if any experience in this process, and a single stylesheet error often prevents the generation of any useful output.
Visual data mapping tools have been created to accelerate the implementation of XSLT stylesheets. These tools, however, are only useful to author a particular stylesheet format (e.g., XSLT for transforming XML to HTML). There remains a long felt need in the art for solutions that can be used to create stylesheets for multiple output formats. The present invention addresses this need.